The present embodiments relate to phase change ink compositions characterized by being solid at room temperature and molten at an elevated temperature at which the molten ink is applied to a substrate. These phase change ink compositions can be used for ink jet printing. The present embodiments are directed to a novel phase change ink composition comprising an amorphous component, a crystalline material, and optionally a colorant, and methods of making the same.
Ink jet printing processes may employ inks that are solid at room temperature and liquid at elevated temperatures.
The phase change ink compositions are characterized by being solid at room temperature (e.g., 20-27° C.) and molten at an elevated temperature at which the molten ink is applied to a substrate. While current ink options are successful for porous paper substrates, these options are not always satisfactory for coated paper substrates.
In general, phase change inks (sometimes referred to as “hot melt inks”) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jetting temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording medium, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks for color printing typically comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. In a specific embodiment, a series of colored phase change inks can be formed by combining ink carrier compositions with compatible subtractive primary colorants. These phase change inks can comprise four component dyes or pigments, namely, cyan, magenta, yellow and black, although the inks are not limited to these four colors. These phase change inks can be formed by using a single dye or pigment or a mixture of dyes or pigments.
Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording medium (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the recording medium, so that migration of ink along the printing medium is prevented and dot quality is improved.
While the above conventional phase change ink technology is successful in producing vivid images and providing economy of jet use on porous papers, such technology has not been satisfactory for coated substrates. Thus, while known compositions and processes are suitable for their intended purposes, a need remains for additional means for forming images or printing on coated paper substrates.
As such, there is a need to find alternative compositions for phase change ink compositions and future printing technologies to provide customers with excellent image quality on all substrates. It is also desired to provide a phase change ink having significantly improved ink robustness, fold offset and rub resistance. Curable phase change inks using amide resin designs have significantly improved ink robustness, fold offset and rub resistance when compared to phase change inks that use waxy materials or other phase-change inks. To test robustness of prints, inks were K-proofed on coated paper (DCEG: Xerox Colour Elite Gloss, 120 gsm). The K-proof sample was duplicated for scratch, fold, and fold offset examination. Then, the K-proofs were spread by feeding each print through a Typhoon fixture at 1 inch/second at a drum and paper temperature of 50° C. with the ink surface facing the transfix drum.